The invention relates to a process for the measurement of the relative movement between loose raceways and a revolving drum mounted in the raceways which is driven by a motor.
For the mounting of revolving drums, raceways and rollers are used. Recently, so-called loose raceway constructions are used. In the case of these raceway constructions, a predetermined difference of diameter is required as a result of the mounting in order to be able to mount the rings on their seating surface. A slight clearance (play) must also exist in the operation in addition in the case of heated revolving tubes, in order that the ring may migrate towrd the revolving tube with a slight relative movement during standard operation. The clearance between the raceways and the furnace however must be kept as small as possible in order that a stronger fulling effect be avoided and that the ring increases the rigidity of the tubular drum. In the case of larger deformations of the tubular drum the insertions, in the case of fired revolving furnaces, the fire-resistant brick linings will be destroyed.
On the other hand however and particularly in the case of inside fired revolving furnaces, the play of the raceways must not be too small, since otherwise the revolving tube will be constricted below the stiffer raceways, which likewise could lead to destruction of the fire-resistant lining.
Furthermore, as a result of a too quick heating up process the raceways are not heated and expanded as quickly as the revolving tube, so that the latter becomes constricted. This likewise will lead to the above mentioned damage.
In order to avoid this type of damage, the relative play of the raceways in relation to the revolving tube is observed by individuals during the dangerous phase. It is possible only to control the starting phase, however. A continuous evaluation during the production phase is not possible, although even in the case of this operational phase constrictions may occur as a result of a sudden drop in clearance or damage to the brick lining.
Therefore, the present invention is directed towards a process of the initially mentioned type and an apparatus for this process which continuously determines the relative movement between the raceways and the revolving drum and which sounds an alarm in the case of danger.
The solution of this task consists in the fact that according to the present invention pulses are created on the raceways by way of a contactless pulse generator in the area of the motor shaft and of the gear input shaft and by way of contactless pulse generators on the raceways, the difference of the pulses being determined for a predetermined value for the rotary drum and for the effectively measured value in the case of one or several revolutions of the raceways and the difference being recalculated for the relative movement. The number of pulses emanating from the pulse generator in the area of the motor or gear input shaft is constant for one or several full revolutions of the motor, and the rigid coupling between the drive and the drum for one or several full revolutions of the drum is independent of the speed of the rpm regulable drive, while the pulses for one or more revolutions of the raceways covered by the same pulse generator are larger by their portion of relative movement.
In a development according to the present invention, the pulses originating from the pulse generator in the area of the motor or gear input shaft are put into counters which are started or stopped by each impulse respectively multiple of it, originating from the raceways and the number of the pulses between one or several start/stop pulses of the raceway can be compared with the one or the several predetermined values for the revolving drum.
With the help of an electronic circuit one can calculate the relative movement from the pulse difference and this can either be recorded and written down digitally or analogously.
In the case of dropping below a predetermined border value for the relative movement an acoustic or optical alarm can be operated, and a blower for cooling the furnace jacket or an arrangement for the lubrication of the tubular jacket below the raceways put into operation.
The process according to the present invention has the decisive advantage that it is possible to operate continuously with optimal play between the raceways and the revolving drum and thus to increase considerably the durability of the fire-resistant brick lining of the revolving drum.
Furthermore the system may have a calculator for the recalculation of the difference of pulses to the relative speed.
In a further advantageous development of the apparatus according to the invention, the pulse generators on the raceways can be watercooled in the case of inside fired revolving drums.
The measuring arrangement according to the present invention is distinguished by its simple development and its great safety of operation. Since no wear occurs, continuous maintenance operations are not required.